Physics: CUET Mock Test - 8 - JEE MCQ

# Physics: CUET Mock Test - 8 - JEE MCQ

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## 30 Questions MCQ Test - Physics: CUET Mock Test - 8

Physics: CUET Mock Test - 8 for JEE 2024 is part of JEE preparation. The Physics: CUET Mock Test - 8 questions and answers have been prepared according to the JEE exam syllabus.The Physics: CUET Mock Test - 8 MCQs are made for JEE 2024 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for Physics: CUET Mock Test - 8 below.
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Physics: CUET Mock Test - 8 - Question 1

### A capacitor of capacitance 5μF is charged to a potential difference of 20V. After that, it is connected across an inductor of inductance 0.5 mH. What is the current flowing in the circuit at a time when the potential difference across the capacitor is 10 V?

Detailed Solution for Physics: CUET Mock Test - 8 - Question 1

Given: V2 = 10 V; V1 = 20 V; C = 5 μF; Inductance (I) = 0.5 mH
Initial charge on the capacitor (q1) = C × V1 = 5 × 10-6 × 20 ……………….1
q1 = 10-4 C …………..B
The instantaneous charge on the capacitor as the capacitor discharges through the inductor ⇒ q2
q2 = q1cos (ωt) ⇒ q2/q2 = cos (ωt) ………………..A
Also, q2 = C × V2 = 5 × 10-6 × 10 …………………….2
q2 = 0.5 × 10-4 C
From 1 and 2 ⇒ q2/q= V2V1 ⇒ q2/q2 = 0.5 = 1/2
From equation A, we can equate as follows ⇒ cos (ωt) = 12
ωt = π/2 rad ………………..3
For an LC circuit ⇒
The current through the circuit is given as:
Current (I)=-dq/dt
Charge decreases with respect to time, so, dq/dt obtained will be negative and this is why we add a negative sign to make a current

Physics: CUET Mock Test - 8 - Question 2

### What is the most common application of LC oscillators?

Detailed Solution for Physics: CUET Mock Test - 8 - Question 2

The most common application of LC oscillators is radio transmitters and receivers. LC oscillators have good phase noise characteristics as well as offer ease of implementation. Due to these factors, LC oscillators are most commonly used in radio-frequency circuits.

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Physics: CUET Mock Test - 8 - Question 3

### Find the true statement.

Detailed Solution for Physics: CUET Mock Test - 8 - Question 3

When we are connecting a charged capacitor to an inductor, the electric current in the circuit and charge on the capacitor undergoes LC oscillations. All the others are incorrect statements regarding LC Oscillations.

Physics: CUET Mock Test - 8 - Question 4

Give the SI unit of self-inductance.

Detailed Solution for Physics: CUET Mock Test - 8 - Question 4

The self-inductance of a coil is said to be one henry if an induced emf of one volt is set up in it when the current in it changes at the rate of one ampere per second. Self inductance is defined as the induction of a voltage in a current-carrying wire when the current in the wire itself is changing.

Physics: CUET Mock Test - 8 - Question 5

Identify the factor on which self-inductance does not depend.

Detailed Solution for Physics: CUET Mock Test - 8 - Question 5

Self-inductance is directly proportional to the number of turns and the area of cross-section. The self-inductance of a solenoid increases μr times if it is wound over an iron core of relative permeability μr.

Physics: CUET Mock Test - 8 - Question 6

Identify the factor on which mutual inductance does not depend.

Detailed Solution for Physics: CUET Mock Test - 8 - Question 6

The mutual inductance of two coils is the property of their combination. It does not matter which one of them functions as the primary or the secondary coil. Hence, mutual inductance does not depend on reciprocity.

Physics: CUET Mock Test - 8 - Question 7

Calculate the mutual inductance between two coils if a current 10 A in the primary coil changes the flux by 500 Wb per turn in the secondary coil of 200 turns.

Detailed Solution for Physics: CUET Mock Test - 8 - Question 7

NΦ = MI
200 × 500 = M × 10
M = 104 H

Physics: CUET Mock Test - 8 - Question 8

What is the self-inductance of the coil, if the magnetic flux of 10 microwebers is linked with a coil when a current of 5 mA flows through it?

Detailed Solution for Physics: CUET Mock Test - 8 - Question 8

Self-inductance = Magnetic flux / Current
Self inductance = 10×10-6 / 5 × 10-3
Self inductance = 2 × 10-3 H
Self inductance = 2mH

Physics: CUET Mock Test - 8 - Question 9

Determine the self-inductance of a coil, which has a magnetic flux of 50 milliwebers that is produced when a current of 5 A flows through it?

Detailed Solution for Physics: CUET Mock Test - 8 - Question 9

Self-inductance = Magnetic flux / Current
Self-inductance = 50×10−3/5
Self-inductance = 1 × 10-2 Wb

Physics: CUET Mock Test - 8 - Question 10

What is the relative permeability of an air-core inductor, if its self-inductance increases from 0.5 mH to 50 mH due to the introduction of an iron core into it?

Detailed Solution for Physics: CUET Mock Test - 8 - Question 10

Physics: CUET Mock Test - 8 - Question 11

Which of the following is the unit of mutual inductance?

Detailed Solution for Physics: CUET Mock Test - 8 - Question 11

Mutual Inductance is the interaction of one coils magnetic field on another coil as it induces a voltage in the adjacent coil. Unit of Mutual inductance = V / As−1.
SI unit = VsA-1.

Physics: CUET Mock Test - 8 - Question 12

Write the dimensions of self-inductance.

Detailed Solution for Physics: CUET Mock Test - 8 - Question 12

Self-inductance =

Magnetic flu x Current

Self-inductance = [M L2 T-2 A-2]

Physics: CUET Mock Test - 8 - Question 13

Which of the following is another term for magnetization?

Detailed Solution for Physics: CUET Mock Test - 8 - Question 13

Magnetization is also termed as magnetic polarization. Magnetic polarization is basically a balance between the magnetic flux density in a space which is devoid of matter and the magnetic flux density in a space with matter, i.e. in a material.

Physics: CUET Mock Test - 8 - Question 14

Find the false statement.

Detailed Solution for Physics: CUET Mock Test - 8 - Question 14

The statement magnetic intensity and intensity of magnetization are the same is the false one. They are not the same. When a magnet is entering a magnetic field, then the poles of the magnet experiences certain forces. Magnetic intensity refers to the measure of these forces. But, the intensity of magnetization explains the change in the magnetic moment of a magnet as a function of volume. All the other statements are valid.

Physics: CUET Mock Test - 8 - Question 15

Which one of the following is feebly repelled by a magnet?

Detailed Solution for Physics: CUET Mock Test - 8 - Question 15

Diamagnetic materials are those which when placed in a magnetizing field are feebly magnetized in a direction opposite to that of the magnetizing field. Therefore, it is feebly repelled by a magnet. Example: zinc, gold, etc.

Physics: CUET Mock Test - 8 - Question 16

Which among the following has a relative permeability much larger than 1?

Detailed Solution for Physics: CUET Mock Test - 8 - Question 16

The relative permeability of ferromagnetic materials is much larger than 1. Ferromagnetic substances are those, which when placed in a magnetic field are strongly magnetized in the direction of the magnetizing field, i.e., it is strongly attracted by a magnet.

Physics: CUET Mock Test - 8 - Question 17

Arrange the following in the increasing order of magnetic susceptibility.

Detailed Solution for Physics: CUET Mock Test - 8 - Question 17

Diamagnetic materials have a small and negative value of magnetic susceptibility. Paramagnetic materials have a small and positive value of magnetic susceptibility and ferromagnetic materials have a large and positive value of magnetic susceptibility.

Physics: CUET Mock Test - 8 - Question 18

Pick out the temperature at which iron becomes paramagnetic?

Detailed Solution for Physics: CUET Mock Test - 8 - Question 18

Iron is a ferromagnetic material. Ferromagnetism decreases with a rise in temperature, and above a certain temperature called “Curie’s temperature,” ferromagnets become paramagnets. For iron, it is approximately, 800 °C.

Physics: CUET Mock Test - 8 - Question 19

Pick out the material that cannot be used to make permanent magnets.

Detailed Solution for Physics: CUET Mock Test - 8 - Question 19

Permanent magnets are made up of materials having high retentivity, high coercivity, and high permeability such as steel. Other suitable materials for making permanent magnets are alnico (an alloy of iron, aluminum, nickel, copper, and cobalt), cobalt steel, and ticonal. That leaves zinc as the one that cannot be used to make permanent magnets.

Physics: CUET Mock Test - 8 - Question 20

Find the true statement.

Detailed Solution for Physics: CUET Mock Test - 8 - Question 20

The magnetic susceptibility of diamagnetic materials doesn’t depend upon temperature. This is often because there’s an outsized barrier between the bottom state and therefore the excited states of diamagnetic substances. Hence, it remains constant during the change of temperature. All the other statements are false.

Physics: CUET Mock Test - 8 - Question 21

Identify the expression for Curie’s constant from the following.

Detailed Solution for Physics: CUET Mock Test - 8 - Question 21

Curie’s law in magnetism states that the magnetic susceptibility of paramagnetic materials is inversely proportional to its absolute temperature and it is given by:
χm = C/T

Physics: CUET Mock Test - 8 - Question 22

Which one of the following, when suspended freely, slowly sets itself parallel to the direction of the magnetic field?

Detailed Solution for Physics: CUET Mock Test - 8 - Question 22

Paramagnetic materials are those when suspended freely inside the magnetic field, it slowly sets itself parallel to the direction of the magnetic field. When placed in a non-uniform magnetic field, it tends to move from weaker to a stronger magnetic field.

Physics: CUET Mock Test - 8 - Question 23

Identify the direction in which a thin long piece of magnet comes to rest when suspended freely.

Detailed Solution for Physics: CUET Mock Test - 8 - Question 23

When suspended freely, a thin long piece of magnet comes to rest nearly in the geographical north-south direction. When placed in a non-uniform magnetic field, it tends to move from weaker to stronger magnetic field.

Physics: CUET Mock Test - 8 - Question 24

Give the SI unit of magnetic dipole moment.

Detailed Solution for Physics: CUET Mock Test - 8 - Question 24

The magnetic dipole moment of a magnetic dipole is defined as the product of its pole strength and magnetic length. The SI unit of magnetic dipole moment is ampere metre2 (Am2). Magnetic dipole moment is a vector quantity and is directed from south to north pole of the magnet.

Physics: CUET Mock Test - 8 - Question 25

A magnetic dipole of length 10 cm has pole strength of 20 Am. Find the magnetic moment of the dipole.

Detailed Solution for Physics: CUET Mock Test - 8 - Question 25

Magnetic dipole moment = Pole strength × Magnetic length.
Magnetic dipole moment = 20 Am × 0.1 m
Magnetic dipole moment = 2 Am2.

Physics: CUET Mock Test - 8 - Question 26

A bar magnet of the magnetic moment 5 Am2 has poles 20 cm apart. Calculate the pole strength.

Detailed Solution for Physics: CUET Mock Test - 8 - Question 26

Magnetic dipole moment = Pole strength × Magnetic length.
Pole strength = Magnetic dipole moment / Magnetic length
Pole strength = 5 / 0.2
Pole strength = 25 Am.

Physics: CUET Mock Test - 8 - Question 27

A magnetized needle of the magnetic moment 20 JT-1 is placed at 60o with the direction of the uniform magnetic field of magnitude 9 T. What is the torque acting on the needle?

Detailed Solution for Physics: CUET Mock Test - 8 - Question 27

Torque, τ = mBsin (θ).
Given: m = 20 J/T; B =9 T; θ = 60o
τ = 20 JT-1 × 9 T × sin(60o)
τ = 155.8J.

Physics: CUET Mock Test - 8 - Question 28

A magnet can only repel another magnet. So, ‘X’ is a surer test of magnetism. Identify X.

Detailed Solution for Physics: CUET Mock Test - 8 - Question 28

A magnet can attract another magnet or a magnetic substance like iron. However, a magnet can repel another magnet only. So repulsion is the surer test of magnetism.

Physics: CUET Mock Test - 8 - Question 29

Which of the following is a natural magnet?

Detailed Solution for Physics: CUET Mock Test - 8 - Question 29

Pieces of naturally occurring iron ore, lodestone or magnetite had the property of attracting small pieces of iron. Hence, magnetite is a natural magnet. All natural magnets are permanent magnets, meaning they will never lose their magnetic power.

Physics: CUET Mock Test - 8 - Question 30

Which of the following is not a basic property of magnets.

Detailed Solution for Physics: CUET Mock Test - 8 - Question 30

Attractive property, directive property and the law of magnetic poles are some of the important properties of magnets. So unlike electric charges, magnetic monopoles do not exist. Every magnet exists as a dipole.

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